(1) Field of the Invention
This invention relates to an inhibitor, called bestatin, of aminopeptidase B, leucine aminopeptidase and bleomycin hydrolase which is produced by aerobic cultivation of streptomyces and includes processes for its production by fermentation and for its extraction.
(2) Description of the Prior Art
Bestatin is a substance found and isolated from culture broth of a streptomyces and has interesting biological and physiological activities. Namely, bestatin has substantially no antibacterial activity, but exhibits a weak inhibition of growth of mammalian cells including cancer cells and a strong inhibition of aminopeptidase B, leucine aminopeptidase and bleomycin hydrolase. Based on inhibition of bleomycin hydrolase, it exhibits a strong synergistic activity with bleomycin in inhibiting tumors. Therefore, bestatin is very important not only in treatment of squamous cell carcinoma by bleomycin, but also in analysis of biological functions and disease processes.